Typical rigid or inflexible couplings (e.g. steel) may have high strength but in many applications such couplings exhibit certain inherent disadvantages. For example, rigid couplings do not allow for misalignment of the driving member and the driven member. Further, rigid couplings transmit torsional vibration and shocks from the working portion of the device to the power supply (e.g. an electric motor or internal combustion engine). The effect of such vibration and shocks may be, for example, increased wear on the drive train and damage to the power supply. Rigid couplings also transmit a considerable amount of noise.
Although certain types of flexible couplings have previously been described, none of such couplings have provided the advantages provided by the flexible couplings of the present invention. For example, the coupling described in U.S. Pat. No. 2,586,567 is designed in a manner such that metallic inserts at both ends of the coupling reinforce the coupling. In U.S. Pat. No. 4,098,096 the use of non-metallic inserts is described for press-fitting between a steel drive coupling and metallic involute shafts; thus, the non-metallic inserts are totally contained by metallic components. Similarly, U.S. Pat. No. 2,259,460 describes a resilient bushing which is entirely contained between metallic components, and U.S. Pat. No. 2,974,502 describes another type of non-metallic bushing or insert which is also entirely contained within metallic components.